Here is a nice post about the advantages of Apache Spark over more traditional Hadoop.  They are numerous and at Big Data Lens we are adopting this important technology into our work. 

While you are at it be sure to check out the guys at databricks.  The founders helped invite Spark so they know what they are doing in simplifying and managing spin up / down of Spark clusters and then tacking on a nice GUI for developing your scripts and machine learning models.  Do yourself a favor and invest 20 minutes of your time watching this video to see how it all ties together.